Origin and characteristics of salt affected soils in Mafiga - Chamwino lowland area Morogoro - Tanzania
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Date
1996
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Sokoine University of Agriculture
Abstract
Salt affected soils is a major problem limiting crop growth in majority of the flood plains in Tanzania, the Mafiga-Chamwino lowland in Morogoro district being one of them. A detailed study was conducted to investigate the distribution and characteristics of salt affected soils in the Mafiga-Chamwino lowland in Morogoro district. The objectives were characterisation, classification and mapping the extent of distribution of salts; determination of spatial distribution of salts and corresponding crop performance; and investigation of the sources of salt accumulation.
Distribution of different types of soils was studied by carrying out grid survey at 50 m spacing while the spatial distribution of salts and the corresponding crop performance was done at 10 m spacing. The corresponding maps were drawn at a scale of 1:10 000 and 1:1 000 respectively. Detailed laboratory characterization was done on the salt affected soils, surface and ground waters as well as rocks from the weathering front.
Four- types of soils: Gleyic Solonchak, Chromic Luvisols, Gleyic Luvisols and Sodic Solonchak exist in the studied area. These were categorized as saline soil, intergrade between sodic and normal soil, sodic soil and saline-sodic soil respectively. The calcium-magnesiumand sodium-calcium types of cation salinization, and sodium carbonate-chloride anion types of salinization dominated in the soils. Large variations of salinity and alkalinity accompanied by corresponding rice crop performance occurred at a short distance in the area studied. Leaching from the weathering of the dominating basic rocks in the vicinity of the study area accounts for the salinization of both surface and ground waters. These waters are the primary source of salts in the soils. Fluctuation of the ground water determines salt distribution in the soil solum.
Each of the four soils requires a different approach in order to control salt problems.
Description
Dissertation
Keywords
Soils, Salt, Sodic soil